Safety lock electrical receptacle and plug therefor



2 Sheets-Sheet l C. H- WHITLOCK ATTORNEY.

SAFETY LOCK ELECTRICALRECEPTACLE AND PLUG THEREFOR Filed May 24, 1948 FIG 3.

Oct. 24, 1950 Oct. 24, 1950 c. H. WHITLOCK 2,527,382

,SAFETY LOCK ELECTRICAL RECEPTACLE AND PLUG THEREFOR Filed May 24, 1948 2 Sheets-Sheet 2 INVENTOR. CHARLES H-WHITLOCK 2% A TTORNE Y.

Patented Oct. 24, 1950 SAFETY LOCK ELECTRICAL RECEPTACLE AND PLUG THEREFOR Charles H. Whitlock, El Dorado, Kans., assignor o'f o'ne-eighth to Walter F. McGinnis, one-sixteenth to Henry C. Cox, one-sixteenth to Jack Webb, and one-sixteenth to Stewart Elton McCreight; all f El Dorado, Kans.; one-sixte'enth to Harry Last and one-sixteenth to Dorothy Leon Last; Leon, Kans.; and one-sixteenth to Clyde 0. Graham and. one-sixteenth to P. A. Fonts, both of El Dorado, Kans.

Applicatiori'M'ay 24, 1948, Serial No.'28,845

. i 1 t v My invention relates: to a safety lock receptacle and attachment plug. n

An object of this. invention is toprovide anelectrical convenience; outlet and plug for use therein in which the plug cannot be pulled therefrom, as it can in the conventional type plug and receptacle. I

Another object of this invention is to provide a device of the kind mentioned in which the contact points of the plug contact a large area of surface of the contact points of thereceptacle thereby providing an electrical connection having a large capacity whereby there will be little or no voltage drops through the connection.

A. still further object of the invention is to provide a device of the kind mentioned in which the several parts. of the device are sturdy and well supportedto. insure long life and high efficiency of the device.

Another object of the invention is to provide a device of the kindmentioned in which the plug can be quickly and properly inserted in the receptacle. V n V v Another object of the inventioni's to provide a device of the kind mentioned in which the ends of the wires of an extension cord will be automatically bent and pressed into permanent con.- tact with thecontact elements of the plug when the wires are placed in position in the plug and the parts of the plug are assembled.

Another object of the invention is to. provide a device of the kind mentioned that simple, neat in appearance, and one that is inexpensive to make and buy;

Now referring to the accompa nying drawings in which similar numerals of reference designate the same parts throughout the several figures of the drawings; Fig. 1 is a side view ofj the plug. Fig.-1A is a fragmentary" top plan view of the plug shown in Fig. l. V Q t v Fig. 2 is a sectional View through the plug, the view being as seen from the line II-II in Fig. 1 and looking in the direction of the arrows. v

Fig. 3 is a bottom plan view of the plug shown in Fig. 1. .7 n I Fig. 4 is a sectional view through a modified form of the plug, the view being as seen from the line IV-IV in Fig. 5 and looking in the direction of the arrows.

Fig. 5 is a bottom plan view of the modified form of the plug shown in Fig. 4, the lock and guide stem of the plug being removed for convnince of illustration.

Fig. 6 is a front face view of a duplex rece'ptacle for receiving'th'e above mentioned plug.-

4. Claims. (01.173-330) 2 Fig. 7 is a sectional and side view of the plug receptacle. the view being as seen from the line VII-VII in Fig. 6 and looking in the direction of the arrows.

' Fig. 8 is a sectional view through the plug re- "c'eptacle; the view: being as seen from the line tioned, one on.eithe'r:.side of the strip [2.

contact elements-shown inFigure 9 and the con- VIII-VIII in Fig. 6 and looking in the direction of the arrows.

Fig. 9 is a perspective view of one of the receptacle contact elements, both contact elements in the receptacle being identical.

In the drawings'is shown the receptacle de-- vice which comprises a blockv ID, the central portion of which-is provided. with a pair of parallel slots II and Ila. The block. I e is provided with a pair of contact elements Afiand B,-.that are identical and are'constructed as shown in Figure 9. The contactv points A and 13 comprise a strip 12 of metallic-material and having. downwardlyturned leg'fielements I3 and [4, that are' posi- The leg 13 is'pr ovided-withla'hole [5 to receive a screw IS. The outer ends :of. the strip 12 are bent into hook'formations. I! and liljeach'ofwhich are. directed in the same direction as 'shown'iin Fig. 9". 'Ehes'e =contact elements, as

shown in Figure .95 when turned end for endv form right and. left contact points as will later be described.

The block ill is providedwith a pair of the tact elementsare placedone. on. top of, and one along the opposite edges of the block IE to pro--.

vide the contact elements .A and B, shown in Figures 6. '7 and 8. In ass'embling'the contact elements A and B on the block It], the legs M .of

the contact elementseA'and B are. positioned,v one in each of the slots Hand Ila of the block: Illyand the legs 13- ofthe contact elements A and B are positioned", one against each of the;

opposite sides "of- 'the -bl'ock" H The block I!) is provided with'a pair of indentures or holes t9 and [9a that are in registry'with the holes !5' in the legs l3 ofithe contactv elements A andB so as to receive the screws-l6 that are threaded and threaded into a face plate element 25 as a means of rigidly attaching the block ill to the face plate 25.

The face plate 25 has two openings C and D back side of the face plate 25 is provided with a pair of recessed portions 28- and 29 which ex-x tend from their respective notch 26 and 21 to the right to provide space for the hook elements I! and I8 and also to provide space in which to' turn the contact points of the extension plug to the right for contact and receiving purposes in the hook portions I! and N3 of the contact elements A and B and to turn the extension plug to the left for disconnecting purposes as will readily be understood. The opposite ends of the face plate 25 is provided with screw holes H for the reception of screws to hold the device on the wall of a building or in a conventional conduit box.

I While the block In is shown and described as being attached to the face plate 25 by means of screws 23 and 24 it is to be understood that the block l0 may be attached to the face plate 25 by any other suitable method such as cementing or fusing the parts together or even by integral connection at the time of manufacture.

- The extension plug for use with the foregoing described convenience outlet receptacle comprises a body 30 that is preferably cone shaped and having an elliptical shaped base, although it is to be understood that the body 30 could be any other desired shape. The upper or apex end of the cone 38 is provided withan axially positioned opening 3| from which extend a pair of diverging holes 32 and 33 that end and open into a bore or opening 34 that is axially positioned in the opposite or other end of the body 38, the holes 3'2 and 33 being diametrically positioned to each other across the opening 34. A portion of the body 30 projects upwardly into the opening 3| in a V-shapedformation Illa, the'sides of which slope forward and form a guide for the wires 35 and 36 into the holes 32 and 33.

Diametrically positioned across the opening 34 is a pair of metallic Z-shapecl contact elements 31 and 38, the lower ends of which turn toward each other to form foot elements 310. and 38a, and rest against the upper shoulder 39 of the opening 34. The legs of the Z-shaped contact elements are positioned in recesses formed in the body 30 and the side edges of the opposing feet 31a and 38a are provided with notches 31b and 381) that fit around the edges of the holes 32 and 33 for purposes that will later be described.

As shown in Figure 2 there is a retainer and binding plug 40 that is threaded into the opening 34 for the purpose of entering the contact elements 31 and 38 in their position and also for forcing contact of the wires 35 and 36 with their respective foot elements 31a and 38a as will later be described.

Between the holes 32 and 33 is positioned a bore 4| in the body ID to slidably and revolvably receive a guide pin 42 that is integrally formed on the binding plug 40. The binding plug 40 is also provided with a multi-sided pin 43 that is an integral part of the plug 40 and extends in an opposite direction from the pin 42, the pins 42 and 43 being in axial alignment and also being positioned on the center axis of the plug 40.

The outer ends of thecontact elements 31 and 38 are turned outwardly as at 31c and 380 to overlap a flange formation 44 that is an integral part of the body 10 and provides a space 45 between the contact points 310 and 380 and the bottom of the body III.

In Figures 4 and 5 the plug is shown in a modified form of construction and the modification comprises a sleeve 46 that is pressed into the opening 34 as a definite retainer for the contact legs 31 and 38 in their recesses in the body l0 and the plug 40 is threaded into the sleeve 46 for the same purposes as above mentioned.

In assembling the wires 35 and 36 in the body I!) and connecting them with their respective foot elements 31a. and 38a the insulation is moved from the ends thereof so as to expose a small portion or length of bare wire. The wires are then inserted, one through each hole 32 and 33 until the base ends of the wires project into the opening 34 and beyond their respective foot elements 31a and 38a, whereupon the binding plug 40 may be inserted and screwed into the opening 34 or sleeve 46 and as the plug 40 is turned in a right hand direction it will move toward the feet 31a and 38a and contact the ends of the wires 35 and 36 and bend the end of each wire 35 and 36 over its respective foot element 31a and 38a and as the plug advances it will solidly mash and press the ends of the wires 35 and 36 against their respective foot ele ments 31a and 38a to provide a good electrical tive foot elements 31a and 38a.

In assembling the extension plug in the receptacle the pin 43 will be inserted in the hole 28 whereupon the contact points 310 and 38c will register with and pass through the opening extensions 26 and 21 whereupon the extension plug may then be turned in a right hand direction and the contact points 31c and 380 will move under the plate 25 and in the recesses 28 and 29 and enter into the hook portions l1 and I8 of the.

contact elements A and B. The extension plug may be removed from the receptacle in the reverse order from that with which it was assembled as above described.

It is obvious from the drawings and the foregoing description that the extension plug cannot be attached to, or detached from the receptacle by straight longitudinal movements of the plug relative to the receptacle, but those movements must also be supplemented by a rotary movement of the extension plug in order to contact and complete an electrical circuit so far as the extension plug is concerned. This arrangement always insures the extension plug of maintaining an electrical contact and prevents the extension plug from removal from the receptacle due to accidental pulls on the cord or wires 35 and. 36.

While the foregoing description is that of attacl ing the plug to the receptacle for extension purposes it is also obvious that the plug may be entered into the receptacle and partially turned whereupon the plug will be held in the receptacle prior to the contact point of the plug coming into contact with those of the receptacle. In view of this it becomes obvious that the turning of the plug will serve the same purpose as a switch, and

this may be done without the removal of the plug from the receptacle.

While the device as shown in-the drawings and herein described is probably the preferred form of the device, it is to be understood that such modifications of the device may be employed as lie within the scope of the appended claims without departing from the spirit and intention of the invention. Now having fully shown and described my invention, what I claim is:

1. In an electrical socket and extension plug device therefor; said plug having a body portion, said body portion having an axially aligned bore in each end thereof and the opposing ends'of the said bores being spaced apart, said body portion having a plurality of openings connecting between said bores and positioned adjacent the outer edge of the said bores, a plurality of electrical contact elements, each of said elements having a post portion and a foot element thereon and having a hole in each foot element, said contact elements being positioned in a spaced apart position in one of said bores and having their foot elements bearing on the bottom of said bore and the hole in each foot element being in registry with an afore mentioned hole connecting between said bores, a retainer plug, said retainer plug being'positioned in the bore containing the said electrical contact elements for holding the said electrical contact elements in a fixed position, and threaded means for moving said in a fixed position, and threaded means for more ing said retainer plug toward the foot element of each of said electrical contact elements for the purpose of binding a wire end between each of said foot elements and the end of the retainer plug for electrical connection purposes, and guide means on the retainer plug for guiding and centering the extension plug device in a receptacle therefor, said guide means having a wrench hold formation thereon by which the retainer plug and said threaded means may be turned for the purpose specified.

3. In an electrical socket and extension plug device therefor; the structure defined in claim 2, said structure being further characterized by the exposed ends of the said electrical contact elements being turned outwardly in radial directions relative to the entire circular assembly of the the said bores being spaced apart, said body portion having a plurality of openings connecting between said bores and positioned adjacent the outer edge of the said bores, a plurality of electrical contact elements, each of said electrical contact elements having a post portion and a foot element thereon and having a hole in each foot device.

4. In an electrical socket and extension plug device therefor; the structure defined in claim 2, said structure being further characterized by the exposed ends of the said electrical contact elements being turned outwardly in radial directions relative to the entire circular assembly of the device in combination with the foregoing defined electrical extension plug structure, a socket for receiving said electrical extension plug, said socket having a body portion and a detachably attached cover plate therefor, means in said body v portion for receiving the guideelement of the said plug, and hook contact elements, one for each contact element, of the extensionplug and carried by the said body portion of the said socket, and means in said cover plate for receiving the contact elements of the plug and permitting the turning of the exposed ends of the contact elements of the plug thereunder as a means of locking the plug in the receptacle prior to the engagement of the contact points of the plug with the contact points of the socket, said plug contact points being engageable with the contact points of the socket upon continued advance turning of the extension plug device.

CHARLES H. WI-HTLOCK.

REFERENCES CITED The following references are of record in the 0 file of this patent:

UNITED STATES PATENTS Number Name Date 1,294,444 Goetzelman Feb. 18, 1919 1,784,236 Jones Dec. 9, 1930 1,956,018 Gilbert Apr. 24, 1934 r 2,032,470 Chirelstein Mar. 3, 1936 

